Never have I done this nor will I ever, but honestly if ALL snakes are 100% for sure healthy and there are multiple hot spots in the enclosure then I don't see why not.

The problem with having only one hot spot is that one snake could get more of the heat in than the others, which can cause the others to get an RI if they don't get the right temperatures. Then if that happens, they'll all be sick.

The only downside I see to keeping Balls together (well in this case since its all females) is that they may get stressed from the other roomies in the enclosure and so any of them could stop eating from the amount of stress (which if too stressed for too long can also cause respiratory distress). I've seen female Balls kept together in vision cages with no problems what so ever, so it's not like this is impossible to pull off.

I'd say try it out and see how it goes, but definitely have multiple hot spots in the enclosure. If any of them go off feed for a long time with no interest in food at all, separate the refusers and keep them seperate from the others. Even separate any that are acting different than normal, just in case.

I'd like to see how this goes, it seems very interesting.

And for a little tip, during feeding time always feed them separate from each other to refrain from them attacking each other because they mistook them for food or if all try to go over one rat.

Hope this helped, maybe someone else can chime in as well for a second opinion.